I'm having a bit of a conundrum. I bought a SIM800c development board off of ebay but the pins are not labeled at all and I have no idea which pins Rx and Tx are. I really want to hook it up to my COM port and test it out with putty. In case you weren't aware, these GSM modules communicate via the UART in AT commands.
Anyways I do have some helpful hints to solve this mystery. Here is a link to the item that I purchased.
You can see a picture of it on there. I also found what looks like my module along with a pinout->
Its not exactly the same as the one that I bought, but its the best thing I was able to dig up. I'm not sure if this is the correct pinout?
I tried hooking it up to some pins labeled "Test pins". There were pins for power and ground, along with two pins, one labeled R and the other labeled T. I thought those must be it, but when I test the AT commands in putty, there is no response from the GSM module. I'm pretty sure these can't be the right pins.
Please someone with knowledge, can you tell me which pins are Rx and Tx? If you have a schematic, please share.
One more thing I'd like to add is that I tried contacting the seller on ebay, but they told me "They are only a customer service and they don't know anything technical. Please research the internet."